SL Upgraded Airport Connecting Issue- Please Help!

Howdy,
I've got a mid 2007 MacBook Pro. I easily and flawlessly upgraded to Snow Leopard the other day and have been using all of its properties seamlessly. Just last night however, as I am browsing the interwebs and trying to watch some video, my Airport cut out on me. We have an old wireless modem, but for the past few years it's been working just fine. I had no issues really with internet accessibility with leopard or snow leopard until now. I've reset the router and modem, and if I want to connect to the internet, I have to be directly plugged into the ethernet. I have yet to try this on another wireless network but here's what happens:

Airport is turned on, searches, and finds my network at home. Usually I have full bars, but it shows only a few. I select the network, it attempts to connect, and after a few seconds, it says Network timeout. It's not a problem with our PC in house either. I've noticed that there have been some issues with network accessibility with other MacRumors users as well and I was wondering if someone could explain to me what's going on. Will I need to take this to the Apple store for "help?" Or has one of you geniuses found an easier approach to do this? I think I'm pretty proficient at computers, esp. Macs, but explaining things like, "search the IP on your DHCP for the IPv4..." will leave me lost. I appreciate any and all help with this issue.

 

Shoot. I have to reinstall it? Well that kinda sucks. Can you explain how I go about doing a "clean install?" I may have done that once before with Leopard when it was giving me problems when I tried to upgrade. I have all my data/ information backed up on time machine. Is that the same as archiving it? Thanks for your help!